Method of freeing pipe jammed in a well



March 27, 1945. J. T. HAYwARD MTHOD OF FREEING PIPE JAMMED IN A WELLFiled oct. 1o, 195s nlv y w` W Q w m v m U .In n f .w 2 HH \|\\|,l. M

Patented Mar. 27, 1945 v METHOD 0F FREEING IIPE-'JAMM IN A WELL John T.Hayward, Tulsa, Okla.4

Application October i0, 1938, Serial No. 234,223

(Cl. 20d-180) 2 Claims.

This invention relates to a method of controlling the deposition ofsolid matter on objects immersed in uids containing solid or semi-solidmatter in suspension therein, and more particularly to an electricalmethod of controlling the deposition of earthy particles on objectsimmersed in an earthy suspensoid.

In numerous industrial operations, streams or bodies of fluidscontaining solid matter are handied or subjected to treatment invarious-ways which involve immersing in the fluids, objects,

such as thermometers, hydrometers, electrodes, pressure gages,viscosimeters, meters and similar apparatus for the several purposesnormally served by these objects. 4In Amany ofthese operations, thetendency of solid or semi-'solid matter contained in the fluid todeposit on the immersed objects adversely affects the emciency of thesef objects to fulfil their normal functions, and may thus seriouslyimpair the efciency of the operations being conducted. For example, inthe drilling of wells by the rotary method, which involves thecontinuous circulation of a stream of mud laden fluid to and from thewell, the physical.

and chemical characteristics of the fluid must be carefully watched andcontrolled throughout the drilling operations in order that dangerousand expensive blow-outs may be prevented and in order to study thenature of the strata traversed by the drill by* observing and measuringthe changes which occur in the character of the circulating fluid. Suchstudy and observation requires the use of various indicating, recordingand measuring instruments which are ordinarily keptv immersed in thestream of mud fluid. Such instruments may be electrical ornon-electrical, depending upon the character of the test to be made. Inpractically every case, however, such instruments, when immersed in themud fluid, become caked or clogged by deposits thereon .of the mudparticles carried by the uid, and are rendered completely inoperative,or ineflicient in perfomance 'of their normal functions, For example,frequently desired, when a thermometer bulb, whether of glass, metal orother material, is immersed in the mud stream for this purpose, it

quickly becomes,l caked with a layer of mud particles which acts toinsulate the bulb and thus render the temperature readings incorrect andunreliable. Or it may be desired to measure the electrical resistance ofthe mud stream, which operation involves immersion of a pair of spacedelectrodes in the stream and. again deposits of mud matter will form onthe electrodes, at least partially'- insulating them, and renderincorrect the resulting resistance readings e In still another case, theviscosity of the mud stream isa physical property, the close control ofwhich ishighly important, and for best results should be continuouslyobserved, However, sev- 'eral otherwise practical forms of viscosimetersfor obtaining continuous measurements of this property have beenydeveloped but all involve the immersion of some part, s'uch as arotating metal cylinder or a tube, in the mud stream whereby theviscosity of the mud uid is obtained. All such viscosimeters havelproven generally inoperative in practice because of the adherence ofthe mud particles to the immersed parts, thereby rendering theVviscosity readings meaninglesa'and since no way had heretofore beenfound to prevent the 'deposition of mud on such parts, these continuousmethods of Y. measuring viscosity had to be abandoned in favor ofintermittent sampling of the mud stream and testing the viscosity of theindividual samples. This method is rather unsatisfactory becauseA of thefrequently rapid and marked changes effected in the mud stream by.contact with subsurface strata, and the individual'samples thus are veryoften not at all representative of any substantial portion of the `mudstream and the viscosities of such samples, therefore, may be entirelymisleading and inaccurate.

Numerous other examples of like-nature may be found in bothwell-drilling operations and in other types of operations, but it isthought that the foregoing examples are sufficiently illustrative ofsome of the problems which are solvedv by this invention.y

The method contemplated by this invention is based upon the phenomenonof electrophoresis f which is defined as the migration of suspendedtemperatures of the mud stream are solid, liquid, or gaseous colloidalparticles under the influence of an external electrombtiye force. Asmost solid particles in suspension inl'liquids generally carry anelectric charge, it is found that if an E. M; F. is impressed upon an4object'in'imersed ina fluid containing such particles, an velectricfield is created' in the fluid about the object causing a migration ofthe charged particles through the fluid in a directionl in accordancerwith the direction of the field and with'the sign of the charge'on theparticles. Thus. if the particles are negatively` .charged and the`field direction is toward the object, the negatively charged particleswill move oppositely to the direction ofthe field and away from theobject. If the particles are positively charged, they will move towardtheobject, but if the eld is reversed, the positively charged particleswill move in the direction of the fleld and away from the object. Inother words, if an lobject is immersed in a fluid containing negativelycharged particles, in order to prevent deposition of the particles onthe object, an electric circuit is established including the object andthe fluid, and an E. M. F. is applied to the circuit to create anelectric field, the direction of which will be toward the object, and

- the negatively charged particles will then migrate way from, or willbe repelled from, the object. If the particles are positively charged,the field direction will be directedr away from the object and theparticles will be repelled therefrom under the influence of theexternally applied E. M. F. vStated in still another way, the methodcomprises making the object of like electrical sign relative to thecharge on the particles in order to repel the particles from the objectand of unlike eiectrical Sign to cause deposition of the particles onthe object whenever such action may be desired.

Another important application of this invention is in releasing objectswhich, when immersed in fluids containing solid or semi-solid stuck orjammed by the settling of the solid or semi-solid matter about theobject, or by the formation of gel-like masses in the fluid, .to such anextent that the objects cannot easily be withdrawn from the iluid.

A very common example of this condition is found -in the well drillingindustry, where drilling tools, pipe and similar objects become stuck inthe drill hole, when for various reasons cuttings and other solid mattercarried by the drilling or well iluids, known in the art as a mud uid,and generally comprising water anda gelforming component such as claysuspended in such a fluid, precipitate from the fluids and settle aboutthe tools orpipe, or when the mud iluid forms a semi-solid gel of suchconsistency that removal of the tools or pipe becomes exceedinglydifficult. By impressing an E. M. F. on the'tool or other object tocreate an electrical field in the fluid in proximity to the object, andby suitably controlling the direction of the field relative to thecharg'e on the particles in the iluid; these particles will be repelledfrom the object, resulting in its release and permitting easy withdrawalthereof Afrom the fluid and the drill hole.

This application of the present invention was described in my formerapplication, Serial Number 199,831, filed April 4, 1938, for Methods ofcontrolling well fluids, and the present application is, therefore, acontinuation-impart of ,my former application'. Y Therefore, a principalobject A more specific object -is to provide an 'elecl trical method forpreventing the deposit ofmud solids on objects. immersed in oil wellmuds.

`matter, particularly in conned spaces, become tion through the well.

An additional ,object is to provide an electrical method for releasingobjects which become stuck or jammed in iluids containing solid .orsemisolid matter,

A further' object is to provide an electrical method for releasingdrilling tools, pipe and the like which has become stuck in the mudlluids within well bores.

Other and-more specific objects of this invention will be readilyapparent from the following detailed description thereof and theaccompanying drawing which illustrate more or less generally apparatussuitable for practicing the new invention.

In the drawing:

' Fig. 1 illustrates a portion of the ilow of a streamof mud uid inconventional rotary well drilling operations and showing an objectimmersed in the mud stream and the electrical circuit employed inconjunction therewith for accomplishing the aforementioned objects ofthe present invention. y

Fig. 2 is an enlarged detail of the significant portion of the apparatusshownk in Fig. l.

Fig. 3 is a view similar to Fig. 2 but showing a diierent objectimmersed in the mud stream.

Fig. 4 is a view showing an assembly of apparatus for releasing adrilling tool and pipe from the fluid in a' well bore.

Referring to the drawing and to Figs. l and 2 in particular, the numeralI designates a conventional well casing through which extends a pipe`2,such as a Conventional string of drill pipe. Mud fluid 3, such as isusually used in well/drilling operations and consisting ordinarily of asuspension of finely ground clay or other earthy matter in vWater orsimilar aqueous suspensoid. is circulated through the welllay-introducing the fluid through pipe 2 throughwhich it ows to thebottom of the well, returning through the annular space between pipe- 2and casing i whence it is` discharged at the surface of the groundthrough a pipe "lnto a conduit such as a mud ditch 5, thence to asettlingpipe 6 where drill cuttings -and other matter are separated fromthe mud fluid, which'is then drawn through a suction pipe 'I'to 'a pump,not shown, which returns-the mud fluid to pipe 2 for recircula- Anobject, such as a vapor pressure thermomeier 8, has its bulb 9 immersedin the mud fluid for the purpose of *observing the temperatures of thefluid as it leaves the well and flows through ditch E. A source ofdirect current IB, which may be a battery, generator or rectifier, hasone terminal connected by a lead H to the bulb 9 of this inventionlis toprovide a method for controlling the depo- .and the other terminal by alead I2 to ground.

The described apparatus is operated in the fol'- low'ing manner in orderto control the deposition of solid or semi-solid mud particles on thebulb. In this case, it is desired to prevent the deposition of the solidmatter on the bulb. Asv

1 positive terminal vto ground. ',Ihe mud ditch 5 is. o f course, alsogrounded. By means of the electric circuit thus established, an. E. M;F. is

impressed upon bulb 9 and an electric field es- .tablished through themud fluid. The surface charged solid particles of the mud fluid, shownin exaggerated size in Fig. 2, will be repelled from l mud matter,andnly very low voltages are required. In the above example, wherethebulb il relatively good conductor, a small standard sized ash lightbattery cell supplied sufficient voltage to keep the bulb clean.Actually only about l to 2 volts was all that was required to keep cleannot only the described thermometer bulb, but also several additionalinstruments which were connected in parallel with the thermometer.Generally speaking, the voltage required will be such as is sufficientonly to create an electric field in the fluid about the objects tobe'kept free of deposits, and will be relatively low, ordinarily,

.. is constructed of metal, such a's iron, which is a but may beincreased, depending upon the intensity of the action desired in keepingAthe objects clean.

Fig. 3 shows the invention applied to prevent deposition of mud matteron electrodes immersed in the mud fluid. The electrodes, designatedI3-l3, are connected to a separate electrical circuit, designatedgenerally by the numeral I4, which is` employed for the purpose ofobtaining electrical measurements of a certain properties of the mudfluid, such as its electrical resistivity. "ll'hisl circuit includes asource of alternating current, a variable resistance, and an alternatingr current voltmeter, as shown in yligure 3. requires that current flowthrough circuit I4, which is independent of the cleaning E. M. F.applied in accordance with this invention. In order to prevent thedeposition of mud matter on the electrodes I3-|3,`whlch'would tend to insulate them and adversely effect the resistivity measurements obtainedtherefrom, the negative terminal of current'source l0 is connected tocircuit l and thepositive terminal of source l0 is then connected `toground, as inthe above example. A small E. M. F. is thiis impressed oncircuit I4 including electrodes I3 and by means of this E. M. F. theelectrodes become negatively charged and thus repel the negativelycharged particles of mud uid 3. The impressed E. M. F. is analogous tothat referred t'o in the electrical arts as a bias E. M. F. having nodirect effect upon the action of the current flowing in the cir. cuitit.

in this case, again, the voltage required will be relatively low but maybe varied or increased depending upon the intensity of the actiondesiredv to keep the electrodes clean.

Fig. 4 illustrates a modification in which cleaningE. M. F. may beapplied, as above described, to a drilling string l5 immersed ir'i themud fluid in a well.

The action is the same as that previously described, in that, byapplication of suilicient F., the particles of the mud fluid arerepelled from'the surface of the drilling string and the frictional andelectrical drag ofthe mud fluid thereon is greatly reduced,v

since the movement of the solid matter away from the string will leavethe string surfaces in contact 'with \a film of lrelatively clean water,which would, of course, offer little resistance vto the movement of thestring, either longitudinally or rotatively.

However, a very important applicationof this tools or'pipe which havebecome stuck in the well. The mud fluids commonly used xin drillingoperations are colloidal suspensions of finely ground clay orotherlsimilar earthy matter in water or similar aqueous suspensoid. Ordinarilythe nature of the colloid is so controlled that the fluid will haverelatively low viscosity and yield strength, suillcient to carrycuttings. from the well but low enough to permit rapid setting o f thecuttings from the fluid .after removal from the well. The colloidcomprising the mud fluid is frequently of such a nature that it willremain iluid and relatively non-viscous as long as it is agitated bymovement through the well, but when allowed to become quiescent, as bystoppage of the circulating pumps, forms a gel of quite considerablestrength. The gelling of the fluid may yalso occur frequently as aresult of chemical changes produced in the fluid by certain of thematerials removed from the sub-surface formations by the drill. 'Forexam-ple, bentonitic materials frequently encountered in wells sharplyincrease the viscosity'and gelling of the mud fluid.

When gelling or thickening of the mud fluids occur in a well, theconsistency of the fluids may become such that the drilling tools orpipe become firmly stuck in the well bore, and'become very difllcult'toremove from the well, sometimes even causing complete loss of the Well.In other cases, the colloidal character of the mud fluid may bedestroyed by action of materials encountered in the well withthe resultthat the clay particles'precipitate from-'the colloidal mud fluid and,upon stoppage of the mud pump, may settle about the tools or^pipe andpack sufllciently to. prevent ready removal thereof from Til inventionin connection with drilling tools and -l pipe which must be frequentlyremoved from the wen and reinseri-.ed therein during the course of thedrilling operations, is in the releasing of such `of tools or pipe intoa well containing mud uid, the mud particles tend to build up on theadjacent surfaces of the tools or pipe and the wall of the well to suchan extent that masses of mud particles are rubbed-off of these surfacesby the longitudinal movement of the tools or pipe in the well and causesame to be jammed in the well. This action is commonly known in the artas balling-up and causes a great deal of dimculty in the running ofpipeand tools in and out of a Well.

In such cases, the present invention is successfully applied to release.the toolsor pipe which has become stuck in the well. This isaccomplished by connecting the negative terminal of the current sourceI0 tothe tool or pipe and applyingl a suitable E. M. F. and making thetool or pipe negative relative to the particles of the fluid.Immediately,l by electrophoresis, those particles which are contact withthe surfaces of the tools or pipe are repelled therefrom, and arereplaced by a sheath of the aqueous suspensoid, thereby releasing boththe frictional and electrical drag of the solid matter upon the tools orpipe and permitting ready withdrawal thereof from the well. A

The E. M. F. may be applied to the entire string cf tools or pipe asillustrated in Fig. 4, or to a portion thereof as may be desired.

In` this case, also, the voltage required will be rele-tively low andmay be varied as desired to hasten the releasing action thereof on thetools. In most cases, 5 to l5 volts per inch of fluid, perpendicular tothe surface of the immersed object. will be suicient to release theobject.

As previously noted, in most known cases inticles in a liquidsuspensoid, the particles will bear a negative charge and in order to.keep immersed objects clean or to release objects stuck in massesofrsuch particles, it is necessary to apply a negative potential to theobjects. However, in the event a suspension contains positively chargedparticles,`it is only necessary to apply a l positive potential to theobjects to accomplish the same purposes.

, is only necessary to direct the field applied to the objects, so as tomakethe objects of unlike polarity relative to the particles of solidmatter and thereby cause attraction and deposit of the matter on theobjects.

' It will be evident from the foregoing', that l y I have disclosed, ingeneral, a method of controlling the deposition of solid or semi-solidmatter, bearing electrical charges, on objects .im-

mersed in a fluid containing such matter, and

particularly an electrical method of preventing the deposition' of suchmatter on objects immersed in uid suspensions of said matter, by-

creating an electric field in the uld adjacent to the objects andcontrolling the direction of the field .to cause the particles of thefluid to migrate away from the objects. In like manner, objects, whichhavebecome stuck or jammed in masses of solid matter, may be releasedtherefrom.

It should be understood that the electric field, wherever used herein,may be produced by a cell, a thermo-couple, a conductor moving in amagnetic field, or electrostatically.

What I claim and desire to secure by Letters Patent is: 1. In a welldrilled-in an earthy formation, the method of releasing a pipe-which hasbecome stuck or jammed in the well, which comprises, establishing anelectric field between said pipe and ground by applying the negativeterminal of a source of unidirectional E. M. F. to said pipe andapplying` the positive terminal of said source to ground whereby sol-idparticles are caused to migrate away from said pipe and release same.

2. The method of -freeing a drill pipe embedded in drill mud in a borehole which comprises connecting said drill pipe to the negative ter'-minal of a source of direct electric current, grounding the positiveterminal of said-.source -of electrical current and maintaining Saiddrill pipe at sufficiently highl negative vpotential with respect to thesurrounding mud to cause repulsion of the mud particles from the surfaceof and to free the pipe.

. JOHNl T. HAYWARD.

